TITLE:   GCN CIRCULAR
NUMBER:  29459
SUBJECT: GRB 210210A: LCO Optical Afterglow Detection
DATE:    21/02/10 16:24:44 GMT
FROM:    Robert Strausbaugh at U. of the Virgin Islands  <robert.strausbaugh@uvi.edu>

R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration:

We observed Swift GRB 210210A (Laha, GCN 29444) with the LCO 1-m Sinistro instrument at the McDonald Observatory, Texas, USA site, on February 10, from 11:31 to 12:02 UT (corresponding to 9.52 to 10.04 hours from the GRB trigger time) with the Bessel R and I filters.

We performed a series of 5x180s exposures in R and I. We clearly detect an optical source in R and I band in stacked images at a location consistent the initial UVOT detection (Laha, GCN 29444).  Using the USNO-B.1 catalog as reference, we calculate the following magnitudes:

R = 19.62 +/- 0.05

I = 19.10 +/- 0.06

These magnitudes are not corrected for galactic extinction.

R.S. is funded by NSF AST grant #1831682